Plants and Animals
Asplenium rhizophyllum Walking fern
Key Characteristics
Small fern forming dense colonies by tip-rooting; fronds lanceolate with heart-shaped bases and very long tapering tips; occurring on large moss-covered dolomite boulders.
Status and Rank
US Status: No Status/Not Listed
State Status: T - Threatened (legally protected)
Global Rank: G5 - Secure
State Rank: S2S3 - Rank is uncertain, ranging from imperiled to vulnerable
Occurrences
| County | Number of Occurrences | Year Last Observed |
|---|---|---|
| Alger | 1 | 2024 |
| Alpena | 1 | 1952 |
| Berrien | 1 | 1994 |
| Chippewa | 7 | 2024 |
| Delta | 1 | 1979 |
| Dickinson | 3 | 2001 |
| Houghton | 1 | 1970 |
| Leelanau | 1 | 1982 |
| Mackinac | 20 | 2024 |
| Menominee | 1 | 1905 |
Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.
Habitat
Found on large moss-covered boulders in northern hardwoods and occasionally conifers within the Niagara Escarpment region. It is also known from alkaline bedrock outcrops in the western Upper Peninsula, from sinkholes in northeastern Lower Michigan, and very rarely on large, rotting, fallen trees in rich forests. The single southern Michigan occurrence is found on sandy conglomerate boulders within a floodplain forest. Topographically this species usually occurs at or above the 700 ft contour line.
Natural Community Types
- Boreal forest
- Limestone cliff
- Limestone lakeshore cliff
- Mesic northern forest
- Mesic southern forest
- Sinkhole
For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.
Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.
Associated Plants
No associate data are known for the three historical state sites for this species. According to Swink and Wilhelm (1994), the species is no longer extant in the Chicago area, but persists in nearby areas in Indiana, where the typical associates include nut-sedge, spike-rush, rush, Canada rush, Kalm's lobelia, common water-horehound, beak-rush, and arrow-grass.
Management Recommendations
Generally requires shade and moist, moss-covered limestone or dolomite boulders. Species is likely sensitive to drying and scorching from overexposure to sunlight. Maintain overstory and minimize development and fragmentation. When possible, leave large tracts of unharvested forests and allow natural processes (growth, senescence, wind throw, fire, disease, insect infestation, etc) to operate unhindered. If forest is being managed for timber, minimize fragmentation, leave long periods of recuperation between harvests (50-70 yrs.), preserve as much area as possible in a forested matrix, and maintain a range of canopy closure comparable to pre-harvest closure.
Survey Methods
Random meander search covers areas that appear likely to have rare taxa, based on habitat and the judgement of the investigator.
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Meander search
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Survey Period: From third week of August to fourth week of October
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References
Survey References
- Elzinga, C.L., D.W. Salzer, and J.W. Willoughby. 1998. Measuring and Monitoring Plant Populations. The Nature Conservancy and Bureau of Land Management, Denver. BLM Technical Reference 1730-1. 477pp.
- Goff, G.F., G.A. Dawson, and J.J. Rochow. 1982. Site examination for Threatened and Endangered plant species. Environmental Management 6(4): 307-316
- Nelson, J.R. 1984. Rare Plant Field Survey Guidelines. In: J.P. Smith and R. York. Inventory of rare and endangered vascular plants of California. 3rd Ed. California Native Plant Society, Berkeley. 174pp.
- Nelson, J.R. 1986. Rare Plant Surveys: Techniques For Impact Assessment. Natural Areas Journal 5(3):18-30.
- Nelson, J.R. 1987. Rare Plant Surveys: Techniques for Impact Assessment. In: Conservation and management of rare and endangered plants. Ed. T.S. Elias. California Native Plant Society, Sacramento. 8pp.
Technical References
- Flora of North America Editorial Committee. 2002. Flora of North America, North of Mexico. Volume 23: Magnoliaphyta: Commelinidae (in part): Cyperaceae. Oxford University Press, New York. 608pp.
- Gleason, H. A., and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. 2nd Ed. The New York Botanical Garden, New York, New York.
- Godfrey, R.K. and Wooten. 1979. Aquatic and Wetland Plants of Southeastern United States. Monocotyledons. University of Georgia Press, Athens. 933pp.
- Holmgren, N.H. 1998. Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the vascular plants of Northeastern United States and adjacent Canada. New York Botanical Garden, Bronx. 937pp.
- Rothrock, P.E. 2009 Sedges of Indiana and the Adjacent States, The Non-Carex Species. Indiana Academy of Science, Indianapolis, IN. 270 pp.
- Swink, F. and G. Wilhelm. 1994. Plants of the Chicago Region, 4th ed. Indiana Academy of Science, Indianapolis. 921pp.
- Voss, E. G. 1972. Michigan Flora. Part I. Gymnosperms and Monocots. Bulletin of the Cranbrook Institute of Science and University of Michigan Herbarium. 488pp.